Grinder pumps are commonly known in the art as being useful in grinding large solid or semisolid materials in liquid in order to form a slurry which is more easily disposable than the solids themselves. These pumps often have an axial inlet communicating with a pumping chamber and a motor driven shaft extending through the pumping chamber and into the inlet. The shaft is used to rotate a cutting disk within an annular ring thereby effecting the grinding action of the pump. An example of such a pump is disclosed in U.S. Pat. No. 4,108,386.
It has been found that the configuration of the cutting disk and annular ring are of paramount importance in the efficiency of grinder pumps. Those skilled in the art expend much effort in identifying the configuration of the cutting surfaces which are most efficient for grinding various materials. For instance, U.S. Pat. No. 4,378,093 discloses a grinder pump cutter assembly specifically adapted to be useful in grinding rubber and other elastomeric substances.
Fibers and string materials are known to cause difficulties for grinder pumps. Because these materials present a relatively small cross section, they are not readily engageable by the cutting surfaces. Compounding the problem is that their long length allows them to wrap around the pump parts such as the disk, the annular ring and the pump shaft. It is therefore desirable that a grinding assembly for a grinder pump not only provides efficient grinding of solids or semisolid materials but also has particular application to grinding fibers and string-like materials.